I played TF2 (Team Fortress 2) for months using only free drivers:
A few days ago, someone told me that they get better performance out of their graphics card when they use proprietary drivers. To test this, I installed the proprietary graphics card driver (the uppermost option in the screenshot) yesterday and restarted my laptop, just to be sure.
My laptop has a 4K screen with scaling set to 2 so font and graphics have the same size as on a full HD display of the same size but font looks much crisper. I also set the resolution in TF2 to 1920x1080 because the fonts in TF2 don't scale so the chat is hard to read and I get a higher frame rate on this lower resolution.
Anyway, so after restarting, everything was small because because the scaling was set to 1. I set it back to 2 in the display settings in Ubuntu but before I attempted to start TF2, I got the idea of doubling down on the proprietary drivers thing and installing the other other proprietary driver (the Unknown: Unknown one in the screenshot), too. I did so and restarted, again. Nothing changed.
After starting TF2, the resolution inside TF2 was set to 4K, too. I changed it to 1920x1080, again, and restarted TF2 (because I know that TF2 has problems when the resolution is changed until it's restarted). After playing a bit (which really got the fans spinning which wasn't the case before), I took a few measurements of the hardware temperatures and noticed that they were much higher (about 20 K higher for every value) than the values of the reference values I took beforehand.
So I closed TF2 and uninstalled both proprietary drivers. I didn't restart my laptop this time but set it to standby after working on it for some time. After waking it up from standby, all windows looked weird and interaction with them was hardly possible at all. After restarting my laptop, everything looked normal, again.
Upon starting TF2, it took the normal loading time but instead of showing me the options to choose a match, it crashed. No error message, I just saw my wallpaper and no open applications in the launcher.
I tried reinstalling the proprietary graphics driver, restarting, and starting TF2. It worked.
I then tried removing the proprietary graphics driver, again, restarting, and starting TF. It crashed, again.
Even removing the game in (via) Steam, restarting Steam, and installing it again, didn't work: When starting TF2 the first time after the fresh install and waiting the normal loading time, it displayed a window titled Engine Error containing this text:
failed to lock index buffer in CMeshDX8::LockIndexBuffer
On subsequent starts, TF2 crashes without displaying this error message.
How do I get TF2 to work with free drivers, again?
I use Ubuntu 16.04.2 64 bit on a laptop with an Intel CORE i7 (Intel® Core™ i7-4720HQ CPU @ 2.60GHz × 8 according to the Details entry in the Ubuntu system settings. The graphics card named in the first screenshot matches what the graphics card sticker on the casing of my laptop says.
